1. Field of the Invention
This invention relates to hydraulic control devices.
In particular but not exclusively the present invention is concerned with hydraulic control devices which are applicable to the control of a plurality of fluid responsive units from a common fluid pressure source.
2. Description of the Prior Art
It is often desirable to be able simultaneously to exert by means of hydraulic devices displacement forces against a body which it is desired to move. In practice, the necessary displacement forces are frequently produced by separate hydraulic units such as rams under the control of pressure fluid from individual sources and under the control of separate and individually operable control elements. Alternatively, hydraulic rams are engaged with the body to be displaced and the operation of the rams is synchronised as far as possible by operating the controls as far as possible simultaneously.
In practice, the desired simultaneous operation is not produced with the result that the separate hydraulic units do not operate together so that the body to be moved is subjected to uneven displacement forces thereby leading to the possibility that the body will not be moved as required.